Figure 4-1. Synchronization Reference Control - Eaton 9315 Installation And Operation Manual

OPERATION
NOTE The Synchronization Reference Control relays are shown under normal conditions.
NOTE Dashed switch position of Synchronization Reference Control Relay 1 shows UPS in the non-master system mode.
4-2
Eaton 9315/9390/9395 Fixed Master Sync Control Installation and Operation Manual
When the two bypass sources regain availability and synchronization, the Eaton Fixed
Master Sync Control provides the non-master system with its own bypass sensing
voltage as a synchronization reference. Before resynchronization occurs, a 15-second
preset time delay ensures the two bypass sources maintain acceptable
synchronization.
To maintain a fault-tolerant arrangement, the Eaton Fixed Master Sync Control
accounts for the following fault conditions or abnormal operating conditions:
S
When the non-master system is synchronized to the master source, a transfer to
bypass disable signal is sent to the non-master system. This inhibits any transfers
to bypass on the non-master system
S
If one UPS system loses its critical load bus voltage sensing, the non-master
system synchronizes to its own bypass source.
S
Dual redundant logic power supplies are incorporated within the Eaton Fixed
Master Sync Control, ensuring both systems remain synchronized even during the
loss of one of the logic power supplies. If one or both power supplies fail, an alarm
is sent back to the slave system indicating a "SYNC CONTROL TROUBLE" alarm.
These power supplies are powered from each system's critical load bus.
S
With a complete loss of logic power to the Eaton Fixed Master Sync Control (due
to component failure or power supply fault), the non-master system synchronizes
to its own bypass source.
(non-master)
UPS
System
Bypass
Voltage
Voltage
RELAY
UPS
SYNCHRONIZATION
REFERENCE
VOLTAGE
Figure 4‐1. Synchronization Reference Control
Master
Output
SYNCHRONIZATION
REFERENCE
CONTROL RELAY
EATON
FIXED MASTER SYNC
CONTROL
S
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